Biunhexium
Biunhexium, also known as eka-'[[Unhexhexium|'unhexhexium]] or element 216, is the temporary name of a hypothetical superheavy chemical element in the periodic table that has the temporary symbol Buh and has the atomic number 216. As of 2012, no attempt has been made to synthesize this element. Nuclear Properties What follows is based on a first-order, liquid-drop assessment of where the outer boundary of the nuclear world is. Assume cautious values for how many neutrons a nucleus with 216 protons can bind (high neutron dripline) and how few it can have before it fissions immediately regardless of how much the structure it can develop stabilizes it (low must-fission curve). Assume, too, that anything that lasts long enough so that protons and neutrons can be treated as particles rather than collections of quarks (is causal) might be a nucleus. Under these conditions, Buh isotopes are theoretically possible between Buh 651 and Buh 965 (see "The Final Element", this wiki). Buh 651 through Buh 761 are expected to decay by beta emission if they don’t fission quickly. Above that value of A, the confident neutron dripline, drops may decay by neutron emission before they can fission. (Structural correction does not affect neutron emission.) Isotopes lighter than Buh 683 need more than twice the structural correction energy needed to prevent fission in worst-case nuclei in the A = 480 region(3). Predicting whether or not the structure a nuclear drop can develop will allow it to survive for the 10^-14 sec required for it to bind an electron and so become an atomic nucleus is not usually possible at this time. Neutron shell closures have been predicted at N = 644, and 524(4). The former may allow some nuclei in the vicinity of Buh 860; it requires only 1.5 MeV structural correction, but is 13% above the confident dripline. The latter may allow some nuclei in the vicinity of Buh 740; it requires 11.5 MeV of structural correction, but lies below the confident dripline. The band Buh 730 through Buh 865 is the most probable location for Buh isotopes. Buh 682 and lighter are implausible, while Buh 866 and heavier are highly unlikely. FORMATION Ions of this element may form when material from roughly 1 km depth is ejected from a disintegrating neutron star during a merger. It is probably impossible for lighter isotopes to form in this way. REFERENCES 3. "Decay Modes and a Limit of Existence of Nuclei"; H. Koura; 4th Int. Conf. on the Chemistry and Physics of Transactinide Elements; Sept. 2011. 4. "Magic Numbers of Ultraheavy Nuclei"; V. Yu Denisov; Physics of Atomic Nuclei, v. 68, no. 7, pp 1133-1137; 2005. (12-03-19) Chemical Properties Electron structure of Buh has not been studied closely, but it is likely to differ significantly from the conventional orbitals found in lower-Z nuclei. While only the innermost electrons would be qualitatively different, other electrons are likely to be quantitatively different from those in lower-Z atoms. Buh is also large enough that nuclear shape may have an effect on electron structure, which might cause different isotopes of Buh to be chemically different. (Which means it is no longer an element in the chemical sense.) Predictions of atomic or chemical properties of Buh are risky. (11-16-19) References # FLW Incorporated; Specialists in Physical Measurement, Testing, Calibration & Control, "periodic table" / "extended periodic table". # no longer valid Category:Undiscovered elements Category:Chalcogens Category:Radioactive